This minimalist bivy cover is made from the popular and super-tenacious 1.1 oz. ripstop nylon. The silicone-impregnated bottom and water-repellant breathable top to provide amazingly lightweight protection for your sleeping bag. It features a mid-length 27" zipper (#4.5 YKK) for easy access, and comes complete with a reusable no-see-um mesh storage bag. It now comes in a mummy shape, as opposed to the old rectangular shape.